1. Field of the Invention
The present invention relates to a rotary compressor and more particularly to a rotary compressor suitable for use in air conditioners and refrigerator and refrigerating machines.
2. Description of the Related Art
As a conventional rotary compressor, reference is here made to one disclosed in Japanese Examined Patent Publication No. Sho 62-11200, which comprises a cylinder, a piston disposed within the cylinder, and a drive shaft for driving the piston, and wherein a small-volume space is brought into communication with a vicinity of a discharge port through a pressure introducing passage for the purpose of reducing noise induced by a pressure fluctuation which occurs within the cylinder (related art 1).
A conventional rotary compressor is also disclosed in Japanese Unexamined Patent Publication No. Sho 63-290980, which comprises a cylinder, a roller disposed within the cylinder, and a shaft for driving the roller, and wherein a small hole is formed in the vicinity of a discharge port in a cylinder end face so as to be partially open to a discharge recess (related art 2).
A further conventional rotary compressor is disclosed in Japanese Unexamined Utility Model Publication No. Sho 60-32585, which comprises a cylinder, a roller disposed within the cylinder, and a rotary shaft for driving the roller, and wherein a space is formed in communication with the interior of the cylinder with a view to reducing noise caused by a pressure fluctuation in the cylinder and an inlet passage which provides communication between the space and the interior of the cylinder is open to the interior of the cylinder at an intermediate pressure portion in order to prevent an increase of input caused by a reverse flow of a compressed refrigerant in the space at an initial stage of the compression stroke (related art 3).
In the above related arts 1 and 2, however, since the small-volume space or the small hole is always kept in communication with a compression chamber in the cylinder, a high-pressure refrigerant at the end of the discharge stroke, which remains in the small-volume space or in the small hole, flows reverse into the cylinder at the initial stage of the compression stroke, with consequent re-expansion and eventual loss.
In the above related art 3, since a space for diminishing the pressure fluctuation is open into the cylinder which is in the suction stroke, so that the refrigerant which remains within the space flows back into the cylinder during the suction stroke, thus giving rise to a loss.